1. Field of the Invention
The present invention relates to a light-emitting device using an organic compound. More specifically, the present invention relates to a light-emitting device that can provide stability and high efficiency by using a metal coordination compound as a light-emitting material.
2. Related Background Art
Applied studies have been vigorously conducted on organic EL elements as light-emitting devices having high-speed response and high efficiency (see, for example, Macromol. Symp. 125, 1-48 (1997)).
Copper complexes can be manufactured at relatively low costs because their raw materials are available at low costs. Sufficiently exploiting the performance of a copper complex enables a low-cost and high-performance organic EL element to be manufactured.
Organic EL elements using copper complexes are disclosed in Japanese Patent No. 2940514 and Advanced Materials 1999 11 No. 10 p. 852 Y. Ma et al. “High Luminescence Gold (1) and Copper (1) Complexes with Triplet Excited State for Use in Light-Emitting Diodes.” However, those EL elements have significantly low luminous efficiency and those publications describe insufficiently the efficiency of those elements. Therefore, it is hard to consider that the properties of the copper complexes are sufficiently exploited. The performance of those elements is not enough for use in displays, lighting, and so on.
Acta Crystallographica Section C C54, 1998, p. 1087 discloses a copper complex having a structure which is relatively similar to that of a compound of the present invention. However, this publication has no description relating to light emission. Moreover, the copper complex cannot be regarded as a light-emitting material because the copper complex emits no light or extremely weak light at room temperature.